technical report on the nechalacho deposit, thor lake project ...

Scott Wilson RPA recommends the use of medium sized mechanized equipment suitable for
headings of 25 to 30 m 2 . This equipment is expected to see relatively low utilization at the initial
planned mining rate. Mechanized equipment will be selected to minimize the direct physical
labour.
Scott Wilson RPA reviewed the geometry of the deposit and the estimated block values to
determine reasonable starting points for stoping such that the early year feed grades would be
as high as practical.
The mineral resources were also reviewed to determine the center of gravity of the deposit and
to determine a central location for the underground crusher.
After initial consideration of the rock conditions it was determined that a reasonable mining
approach would be to mine a sequence of 15 m wide primary stopes followed by extraction of
the intervening 16 m wide secondary stopes after the primary stopes were mined and backfilled.
Stope cuts will be 5 m high and in areas where the zone exceeds 20 m in height the use of long
hole stoping is proposed. In long hole stopes there would be a top access and a bottom access
and the top access would be used for back filling access after mining.
For lower heights the zone can be taken in one or two cuts before filling. The preferred mining
would be to develop along the upper portion of the Basal Zone and then if the height warrants, a
further cut is taken by benching the floor.
Stopes will be mined in a herring bone layout, with stopes up to 250 m long. Access to the
stopes will be through three access ramps located outside the Indicated Resource in the Basal
Zone. The locations of the ramps are shown in Figure 18-4. The access ramps would connect
to a centrally located ore pass and three ventilation raises to surface.
Mine ventilation will be achieved with surface fans forcing air into the mine at the west end of
the deposit and with airflow back along the mining zone and then upcast in the access ramp and
one upcast raise to the north end and one upcast raise to the west end.
Recovery of the secondary stopes is planned by long hole mining with a top and bottom access.
To reduce dilution the primary stopes will be filled with paste fill and a one metre thick skin will
be left on each stope wall. It is expected that half of the skin will break due to blasting but this
loss of ore is offset by the reduction in dilution due to back fill.
GEOTECHNICAL ANALYSIS
The available geo<strong>technical</strong> information from the TLP has been reviewed with the objective of
providing preliminary stope sizing recommendations. Geo<strong>technical</strong> information for the pre-
Technical Report 43-101 – March 13, 2011 Page 18-4
Prepared by Avalon Rare Metals Inc.